The invention relates to a drive and guide arrangement for endless conveyors which are provided with transport members, the drive and guide arrangement including at least one traction member configured as a profiled rubber-link chain having steel cable traction supports. In each of its end regions, the traction member reverses around drive discs or wheels, which are also profiled. On its side facing the transport members, the rubber-link chain is configured as block toothing, and on the opposite side it is configured as drive toothing and cooperates with the transport members by way of connecting and guide members such as rollers or the like.
Plate chains are frequently used as traction members for endless conveyors such as, for example, scraper conveyors, plate conveyors, bucket elevators, moving stairs or escalators. Such chains are machine components which require extensive maintenance, they are subject to wear and are extremely noisy. Due to the so-called polygon effect, only relatively low conveying speeds may be obtained with these chains, and at the same time, great resistance to movement of the chain and of the supporting rollers in the guides must be overcome. Steel chains having supporting and guide rollers are heavy structures and can be pretensioned only unsatisfactorily. Particularly, in side and portal scrapers, if used as endless conveyors, this results in significant chain slackening in the conveying run with negative effects on the operating behavior of the entire equipment. Heavy chains and great resistances to movement at low conveying speeds and at a predetermined conveying performance require larger and therefore also heavier transport members, such as, for example, shovels, buckets, plates, steps or the like. This in turn affects the driving power to be installed and the service weight of the endless conveyor.
DE-A 3,533,774 discloses a suspension of discharge units on scraper conveyors such as bridge-type scrapers, bucket elevators or the like, which have at least one endless driven traction member in the form of a round-link chain. This traction member cooperates by way of lugs with a plurality of discharge units arranged along the traction member, with the discharge units being offset relative to the scratch conveyor by means of further guide members. The traction member, in this case, must be arranged outside of the guide components which have the shape of a double T. If at least two juxtaposed round-link chains are used which are arranged adjacent to one another as traction members, they may be fastened alternately on consecutive discharge units. Compared to plate-link chains, round-link chains of optimum design may attain the same service life, however, the chain speed may be substantially increased. Moreover, a relatively minimal polygon effect is to be expected, resulting in the chain also being able to perform spherical movements without being damaged. Stretching of the chain, which inevitably occurs in the operating state, can be corrected by removing individual chain links. Furthermore, grinding noises of the chain may by reduced by comparison with the band chain.
Even if significant advantages are already obtained here by comparison with the plate chain, it must not be overlooked that steel members are also present here which, on the one hand, cause noises and, on the other hand, tend to wear out quickly, and the removal of chain links must be viewed as labor intensive.
DE-A 2,161,092 discloses a toothed belt equipped with tooth blocks of different heights arranged on both sides of a reinforcement. The tooth blocks of greater height are wider in the longitudinal direction of the toothed belt and form narrower gaps between adjacent flanks than the lower tooth blocks arranged on the opposite side of the reinforcement, with the height of the larger blocks being dimensioned in such a way that the use of supporting rollers and reversal wheels equipped with elevated lateral wheels is possible if suspensions are taken into consideration. The engagement of the drive wheel in the rubber chain results in a relative movement between the toothed chain and the toothed drive. This movement is converted by wear-resistant rollers into a rotational movement in the region of engagement of the wheel so that direct friction between the rubber chain and the toothed wheel is prevented. In a form-locking manner, the driving teeth engage in the roller teeth of the driving wheel, thus ensuring a slip-free drive.
DE-C 1,283,612 relates to a toothed conveyor belt for high speeds and/or high loads including conveyor means attached to the belt. The conveyor belt is provided with toothed blocks of elastic material that face each other on both sides of a reinforcement. On both sides of the reinforcement a transverse bore is recessed in each of the two superposed teeth made of elastic material. A rod is inserted in each of the transverse bores. The ends of the rods which project from the bore are connected to one another by means of parallel connector plates which project over the teeth of the toothed belt and are connected to one another in this region by a further rod which carries the conveying members.
DE-OS (German Unexamined Published Patent Application) 3,447,218 discloses a steep-incline conveyor configured as an endless discharge conveyor. The discharge units are configured as buckets which, in addition to a front clearance angle also have a side clearance angle, with the traction support being able to absorb and transfer lateral forces. The traction support can therefore be configured as a single or multi-run rubber chain having fastening members and steel cables vulcanized into it. The noise level of a rubber chain is significantly lower and the smoothness of running is significantly improved by comparison with a steel chain. Since the number of runs is adapted to the load on the steep-incline conveyor high flexibility is provided. Moreover, rubber chains do not require lubricants in the region of the traction support.
Although rubber chains are traction members that are low in noise and maintenance and do not require lubrication, they do create problems with respect to the displacement of the transport members and the guidance of their rollers. These problems occur with regard to the changing lengths of the rubber-link chain during sprocket wheel reversal, which results in jamming between the rollers and the guides and therefore cause significant wear of the components. The prior art does not provide any satisfactory solutions in this regard.